Wotan Metal Halide Powerstar HQI-T 400W/DV

This lamp is representative of Osram's fourth generation of rare earth metal halide lamp, and was introduced in the mid 1980s. Many aspects of its construction are similar to the third generation design, although this particular lamp is optimised for vertical burning whereas the 3rd generation lamp featured on this website is the equivalent model for horizontal burning. The main difference between the two is in the filling of the arc tube - the horizontal model being dosed with slightly less mercury and modified halide chemistry to account for the more significant upward bow of the arc, whose increased length would otherwise cause a rise in lamp voltage and power dissipatation, with a consequent negative impact on lifetime and colour.

The main technical step forward with this 4th generation lamp is the inclusion of a new gettering system, which combines two distinct kinds of getter. Osram's 1st and 2nd generation lamps employed only a barium getter, and its lack of sorption of hydrogen impurities led to rather short life - these lamps being especially sensitive to hydrogen contamination which causes an increase in the re-ignition voltage of the discharge on each half-cycle of the mains. The 3rd generation lamps introduced a zirconium-aluminium getter but eliminated the barium film, which removes many other gases. That led to a small decrease in lamp efficacy owing to heat conduction loses in the outer bulb, and a lowering of arc tube temperature and halide vapour pressure. This 4th generation lamp employs both getter materials together. During the late 1990s it was replaced by a new single getter which sorbed both hydrogen as well as other gases, and the barium film could then be finally eliminated.
Manufacturer: Osram GmbH
Lamp Power: 360 Watts
Lamp Current: 3.5 Amps
Lamp Voltage: 120 Volts
Cap Type: E40s/45 Ni plated brass + porcelain
Bulb Type: T-46 T-14½ in eighths/inch
Bulb Finish: Clear Borosilicate
Electrodes: Backwound Tungsten No emitter
Arc Length: 48 mm 1 7/8 inch
Atmosphere: DyI3,TlI,CsI | Ar:Kr85 Outer: Hard Vacuum
Luminous Flux: 28,000 lm @ 100 hours
Luminous Efficacy: 78 lm/W @ 100 hours
Colour Temperature & CRI: CCT: 5900K CRI: Ra 85
Chromaticity Co-ordinates: CCx: 0.330 CCy: 0.365
Rated Lifetime: 6,000 hours to 70% flux
Warm-up & Re-strike Time: 2 mins to 80% flux 10-15 minutes
Burning Position: Vertical ± 45°
Overall Length: 285 mm 111/4 inches
Light Centre Length: 175 mm 67/8 inches
Factory: Spandau, Berlin Germany
Date of Manufacture: March 1988 Date Code: qa3
Original / Present Value: £55.21 (1988) £102.31 (2005)
References: 1) Osram Lichtprogramm 1989/90 pp.6.02
2) Osram UK Buyers Guide April 1988 pp.70
3) Osram Powerstar HQI Brochure August 1990